Sharing a hearty laugh, CEOs John Wren and Maurice Levy seem headed for a promising merger.

NEW YORK CITY-In a move that could shake up office space in the city, advertising and communication giants Publicis Groupe and Omnicom Group have agreed to merge, becoming the world’s largest advertising firm. The partnership had combined 2012 revenue of $22.7 billion. The newly named Publicis Omnicom Group will have a combined equity market capitalization of approximately $35.1 billion, based on closing prices on July 26th.

The organization’s holding company, Publicis Omnicom Group, will be headquartered in the Netherlands but its main operational offices will remain in Paris and New York. Spokespeople for Publicis and Omnicom did not respond to requests for comment. Tenant representation firms that could have spoken to general office trends in the wake of such a large merger did not respond to requests for comment by press time.

However, the integration of the companies alone is likely to take several years: the merged company will have over 130,000 employees. Its umbrella will be crowded with a who’s who of media firms. Specifically, Publicis Omnicom Group will include iconic the iconic agencies of BBDO, Saatchi & Saatchi, DDB, Leo Burnett, TBWA, Razorfish, Publicis Worldwide, Fleishman Hillard, DigitasLBi, Ketchum, and StarcomMediaVest; as well as OMD, BBH, Interbrand, MSLGROUP, RAPP, Publicis Healthcare Communications GroupProximity, Rosetta, CDM, ZenithOptimedia, Goodby, Silverstein & Partners and others. Many of these firms have a presence in Manhattan.

Current Publicis CEO Maurice Levy said in a press conference that the merger will give the newly formed firm a unique edge. “The world is changing—our clients’ needs and wants are much more complex—and the speed of change in the world is requiring a much broader portfolio of assets. This is something that strategically is very different from any other operation in our industry. It’s meant to help clients grow faster and help them connect to consumers through a number of channels.”

Omnicom CEO John Wren, who admitted the two firms have been in talks for a few months, added, “The stars have aligned. Over the last month, we’ve been able to sort through each other’s concerns and come together in a constructive way. This is an opportunity where I think we’ll be creating new avenues of service.”

Omnicom received financial advice on the transaction from Moelis & Co., while Publicis turned to Rothschild. Legal advisors to Omnicom are Latham & Watkins LLP and De Brauw Blackstone Westbroek N.V. Publicis’ counsel included Wachtell, Lipton, Rosen & Katz; Darrois Villey Maillot Brochier; and NautaDulith N.V.